Field of the Invention
The present invention relates generally to a mobile communication system, and in particular, to a communication apparatus and method for minimizing power consumption by performing a discontinuous reception operation in a mobile communication system.
Description of the Related Art
In general, the mobile communication system employs a discontinuous reception operation as one of the methods for extending a battery life by minimizing power consumption of a terminal. In this case, it is general that the terminal is a terminal in the idle state, i.e., in the state where there is no radio connection for a particular service. The idle-state terminal is characterized in that it checks the presence/absence of a call at a discontinuous reception time, and transitions to reception-on (Rx-on) or reception-off (Rx-off) according to the check result.
As stated above, the terms frequently used in the discontinuous reception operation includes ‘Rx-on’ and ‘Rx-off’, and a brief description thereof will be given below.                Rx-on: It is a state in which a receiver of a terminal is turned on. During the Rx-on period, the terminal performs a normal reception operation. For example, the terminal monitors a control channel during the Rx-on period to detect the presence/absence of its scheduling, and receives downlink data upon detecting the scheduling.        Rx-off: It is a state in which a receiver of a terminal is turned off. Therefore, the terminal minimizes its power consumption through the Rx-off period. That is, during the Rx-off period, the terminal does not monitor the control channel, and during this period, the terminal cannot receive data.        
Generally, in the discontinuous reception operation, the idle-state terminal optimizes a length of the Rx-on period and Rx-off period, thereby minimizing the period for which it unnecessarily operates in the Rx-on state. That is, the discontinuous reception operation prevents the terminal from unnecessarily turning on its receiver, thereby minimizing its entire battery power consumption.
However, in the next generation mobile communication system where various types of services are supported, there is a high possibility that the terminal will be not the above-stated idle-state terminal, but a connected-state terminal that should maintain the connected state for a long time. The connected-state terminal, or the terminal having a radio connection, will perform a different discontinuous reception operation from that of the above-stated idle-state terminal. Accordingly, there is a need to make a discussion on the scenario of a discontinuous reception operation for minimizing power consumption of the connected-state terminal.
This means the need for a detailed discontinuous reception operation of a terminal for supporting various services in the next generation mobile communication system.